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Water solubility

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Description of key information

Water solubility [1,2-bis[dichloro(methyl)silyl]ethane]: not relevant

Water solubility [ 1,2-bis[dihydroxy(methyl)silyl]ethane]: 1E+06 mg/l at 20 -25°C (QSAR)

Key value for chemical safety assessment

Additional information

The requirement to conduct a water solubility study for the submission substance is waived on the basis that it hydrolyses very rapidly to 1,2-bis[dihydroxy(methyl)silyl]ethane and hydrogen chloride.


The silanol hydrolysis product, 1,2-bis[dihydroxy(methyl)silyl]ethane, may undergo condensation reactions in solution to give siloxane dimers, linear and cyclic oligomers and a dynamic equilibrium is established. The overall rate and extent of condensation is dependent on nominal loading, temperature and pH of the system, as well as what else is present in the solution. This condensation is expected to limit the saturation concentration in water to well below the estimated solubility of the monomer. Further information is given in a supporting report (PFA 2016am) attached to Section 13.

The hydrolysis product, 1,2-bis[dihydroxy(methyl)silyl]ethane, is soluble in water based on a solubility of 1E+06 mg/l calculated using a QSAR method. This QSAR method for water solubility cannot be validated because the saturation concentration in water is often limited by condensation reactions rather than lack of true solubility. The prediction is however considered to be valid for environmental exposure modelling and toxicokinetics modelling because it is considered to adequately describe the hydrophilicity of the substance and hence the partitioning behaviour.